main.py

import sys
import os
import subprocess
import json
import re
import argparse
from pathlib import Path
from llm import LiteLLMClient
    
def create_next_app(app_name: str):
    """creates a fresh NextJS app"""
    print(f"Creating Next.js app: {app_name}")

    process = subprocess.Popen(
        f"npx create-next-app@latest {app_name} --yes",
        shell=True,
        stdin=subprocess.PIPE,
        stdout=subprocess.PIPE,
        stderr=subprocess.PIPE,
        text=True
    )

    stdout, stderr = process.communicate()
    
    if process.returncode != 0:
        print(f"Error creating Next.js app: {stderr}")
        sys.exit(1)
    
    print(f"Next.js app created successfully at ./{app_name}")
    return os.path.abspath(app_name)

def get_file_content(app_path, relative_path):
    """get content of a file in the Next.js app"""
    file_path = os.path.join(app_path, relative_path)
    if os.path.exists(file_path):
        with open(file_path, 'r') as f:
            return f.read()
    return ""

def build_prompt(app_path: str, user_query: str):
    """build the prompt for the LLM with current file contents"""
    files = {
        "app/page.tsx": get_file_content(app_path, "app/page.tsx"),
        "app/layout.tsx": get_file_content(app_path, "app/layout.tsx"),
        "app/globals.css": get_file_content(app_path, "app/globals.css"),
    }

    prompt = f"""You are an expert web-application developer. Please build a Next.js web application according to the following user query:
"{user_query}"

The current directory structure is:
app/
— globals.css
— layout.tsx
— page.tsx
public/
... etc...

Here is the current page.tsx which you can overwrite.
###
{files["app/page.tsx"]}
###

Here is the current page.tsx which you can overwrite.
###
{files["app/layout.tsx"]}
###

Here is the current page.tsx which you can overwrite.
###
{files["app/globals.css"]}
###

Important Notes:
- Please return the full completed files- you may also create new files if needed. 
- For each file, specify the file path using ###path/to/file### followed by the code for that file wrapped in triple backticks (```).
For example:
###app/page.tsx###
```tsx
// your code here
```

###app/api/submit.ts###
```ts
// Your code here
```

The code you return will be immediately written to the app and then deployed so ensure that the app will compile and run as intended.
"""
    return prompt

def parse_response(response):
    """parse the LLM response to extract file paths/contents into files dict"""
    file_pattern = r"###(.*?)###\s*```(?:.*?)\n(.*?)```"
    matches = re.findall(file_pattern, response, re.DOTALL)

    files = {}
    for file_path, content in matches:
        file_path = file_path.strip()
        files[file_path] = content

    return files


def write_files(app_path, files):
    """write the files to app dir"""
    for file_path, content in files.items():
        full_path = os.path.join(app_path, file_path)
        os.makedirs(os.path.dirname(full_path), exist_ok=True)

        with open(full_path, 'w') as f:
            f.write(content)

        print(f"Wrote file: {file_path}")


def main():
    parser = argparse.ArgumentParser(description="Generate a Next.js app using an LLM")
    parser.add_argument("app_name", help="Name of the Next.js app to create")
    parser.add_argument("query", help="User query describing app to create")
    parser.add_argument("--model", default="claude-3-7-sonnet-20250219", help="LLM model to use")

    args = parser.parse_args()

    app_path = create_next_app(args.app_name)

    prompt = build_prompt(app_path, args.query)

    # print(f"\Prompt:\n{prompt}")
    
    print(f"Querying LLM ({args.model})...")

    lm = LiteLLMClient(model=args.model)
    messages = [
        {
            "role": "user",
            "content": prompt
        }
    ]

    response = lm(messages)

    # print(f"\LM Response:\n{prompt}")

    files = parse_response(response)

    write_files(app_path, files)

    print(f"\nApp generation complete! your app is ready to be deployed at: {app_path}")
    print("you can deploy it with: cd path/to/app && npx vercel")


if __name__ == "__main__":
    main()